The following terms, defined below, will be used to describe embodiments of the present invention.
Chromatography is the science of separating compounds held in solution. The compounds are separated by flowing the solution through a stationary phase. Compounds held in the solution exhibit different affinity for the stationary phase and separate from each other. Common stationary phases are solids such as a packed bed of particles, beads, fibers, and structures known in the art as “porous monoliths”. These solid stationary phases will be referred to herein as solid phase separation media, or simply, separation media.
Solid phase extraction devices are devices that use a solid stationary phase to perform a chromatographic separation. Common solid phase extraction devices include columns, cartridges and funnel-like devices which have one or more chambers containing a separation media. Particularly in the study of biological processes, it is desirable to work with small volumes. If the sample is obtained from a living organism, such small sample may not be as disruptive as a larger sample. Many biological samples can only be obtained in a small volume.
However, as fluid sample size decreases, the sample becomes increasing difficult to handle without losses. These losses may come from fluid retained on transferring devices such as solid phase extraction devices, pipettes, vials, conduits and cuvettes or evaporation. As used herein, the term “evaporation” refers to the change in phase of a liquid to a gas.